Influence of Propagation on Incidence of Seedborne Bean Common Mosaic Virus in the USDA Phaseolus Germ Plasm Collection. R. E. Klein, Department of Plant Pathology, Washington State University, Pullman 99164-6430. S. D. Wyatt, and W. J. Kaiser. Department of Plant Pathology, Washington State University, Pullman 99164-6430, and USDA-ARS, Western Regional Plant Introduction Station, Washington State University, Pullman 99164-6402. Plant Dis. 73:759-761. Accepted for publication 23 March 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0759.

The influence of propagation on the incidence of seedborne bean common mosaic virus (BCMV) in Phaseolus vulgaris accessions of the USDA germ plasm collection was investigated by comparing seedborne BCMV incidence in original seed lots with that in harvested seed. Propagation in the greenhouse during January through June resulted in a 66% reduction in average seedborne BCMV incidence in 26 accessions. In most accessions, seedborne BCMV incidence was reduced to a level that would allow BCMV eradication by elimination of infected plants without affecting genetic diversity. BCMV spread occurred during the July through December greenhouse increase and in the summer field increase, but no significant change in average seedborne BCMV incidence was detected in the 32 and 42 accessions examined, respectively. Virus spread appeared to be caused by noncolonizing aphids. In the absence of effective vector control, average seedborne BCMV incidence in the P. vulgaris germ plasm collection has apparently reached an equilibrium at about 7%.